Serpentina

Serpentina is a term that most commonly refers to serpentine, a group of greenish magnesium silicate minerals that belong to the phyllosilicate family. The name derives from the snake-like appearance of some serpentinite rocks and from historic use of surface textures. The principal minerals in the group are chrysotile, lizardite, and antigorite. Their general chemical formula is Mg3Si2O5(OH)4, though the exact composition varies with the mineral species. Serpentine minerals are hydrated magnesium silicates formed by the hydration and metamorphism of ultramafic rocks, often in contact with hydrothermal fluids.

Geology: Serpentine-rich rocks, known as serpentinites, commonly form through serpentinization, a low-temperature alteration process. They are widespread in ophiolite complexes and in subduction-zone settings where ultramafic mantle rocks are exposed.

Properties and uses: Serpentine minerals are typically green to olive-green, with a waxy to vitreous luster and a hardness around 3 to 4 on the Mohs scale. They are used as ornamental stones in sculpture and cabochon work. Some varieties, notably chrysotile, have been used commercially as asbestos, which poses health risks when fibers are inhaled, so modern handling and regulation emphasize safety.

Other meanings: In some languages, serpentina can refer to decorative spiral streamers used in celebrations, or to items that snake around in a serpentine fashion, but in geology, serpentine refers to the mineral group.